I’ve blogged about generic ways of getting top 1 or top n per category queries before on this blog. An Oracle specific version in that post used the arcane KEEP syntax: This is a bit difficult to read when you see it for the first time. Think of it as a complicated way to say … Continue reading Getting Top 1 Values Per Group in Oracle →

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In a previous blog post, we’ve advertised the use of SQL EXISTS rather than COUNT(*) to check for existence of a value in SQL. I.e. to check if in the Sakila database, actors called WAHLBERG have played in any films, instead of: Do this: (Depending on your dialect you may require a FROM DUAL clause, … Continue reading An Efficient Way to Check for Existence of Multiple Values in SQL →

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One of jOOQ’s key features so far has always been to render pretty much exactly the SQL that users expect, without any surprises – unless some emulation is required to make a query work, of course. This means that while join elimination is a powerful feature of many RDBMS, it isn’t part of jOOQ’s feature … Continue reading A Hidden Benefit of Implicit Joins: Join Elimination →

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